This invention relates generally to air deflectors for reducing aerodynamic drag on tractor-trailers or similar vehicles and more particularly to an air deflector having a novel deflector panel reinforced by a stiffener to increase its torsional stiffness and permit the use of a single adjustable strut for support and adjustment of the panel.
Due to rapidly increasing fuel costs considerable attention has been given in recent years to improving the efficiency of heavy trucks. One aspect of truck design which has been given particular attention is the aerodynamic configuration of the vehicle. Traditionally, the external configuration of such trucks has been primarily determined by various functional requirements and particularly the need to maximize the volumetric load capacity of the vehicle within given height, width and length requirements. Streamlining was not a major consideration and was not generally considered to be economically justifiable, but the recent sharp increases in fuel costs have altered the economic situation. Because approximately one-half the fuel used by a typical tractor-trailer at highway speeds is spent overcoming aerodynamic drag, measurable savings in operating costs can be achieved by reducing drag on these vehicles.
Ideally this drag reduction should be accomplished without significantly increasing the costs of the vehicles and without sacrificing the advantages of present designs. It has been suggested by others that drag can be reduced by adding various types of aerodynamic control devices to the vehicles. Probably the most common such device is an air deflector which is mounted on the roof of the tractor cab such as those described in U.S. Pat. Nos. 2,863,695 to A. F. Stanm and 3,241,876 to W. S. Saunders. The purpose of these deflectors is to divert a portion of the air flowing over the tractor cab roof upwardly and over the top of the trailer so that it does not impinge on the blunt forward end of the trailer body. The optimum configuration and orientation of such deflectors depends upon a number of variables, particularly the difference in height between the cab roof and the trailer and the gap between the tractor and trailer. Accordingly a number of the deflectors currently available are adjustable to compensate for various trailer configurations. Particularly notable is the adjustable deflector described in U.S. Pat. No. 4,102,548 to T. J. Kangas which can be remotely controlled either by the driver or by an automatic control system designed to optimize the setting of the deflector.
Most of these adjustable deflectors are thin, shell-like structures which are adapted to be pivotally mounted near their forward edge to the roof of the tractor cab. Typically they are held in operating position by two or more struts or braces which extend downward from the deflector to the cab roof as illustrated in U.S. Pat. No. 3,822,910 to Wyley. One problem with using such a support system on a manually adjustable deflector is that in order to adjust it the driver must go through the rather cumbersome process of loosening, adjusting and relocking each of the support struts. Consequently the drivers will often leave the deflector in a fixed but less than optimum position after changing trailers rather than an attempt to readjust it. If the deflector is of the power driven type as described in the Kangas patent, a support system of this type results in added cost and complexity of the adjustable strut mechanism. Either the struts must be simultaneously driven by a single actuator or multiple actuators must be used. These problems would be considerably reduced by the use of a single adjustable strut to support and position the deflector, but the deflectors found in the prior art would not be adequately supported by a single strut. Most of them have relatively low torsional rigidity and probably would not withstand the asymmetric airloading imposed by cross winds or gusts. Also, there is no provision in current deflectors for mounting a centrally located strut to the panel and for carrying relatively high loads that would occur at the attachment point. Accordingly, it is an object of this invention to provide for an air deflector assembly having a novel deflector panel which is torsionally reinforced and adapted for use with a single strut. It is a further object of this invention to provide for a novel air deflector assembly which includes a reinforced deflector panel and a unitary adjustable strut which can be quickly and easily adjusted by the driver either manually or remotely with an actuator.